Dbms_lob.FileOpen failed using remote directory in oracle 10g

Question

when i create a directory with the remote shared path like '\\kf-kjyxp\sharepath\temporary' . then in a pl/sql block i use dbms_lob.fileopen to open bfile object , a failure occurs .but the situation does not happen when i use a local diretory like 'd:\sharepath\temporary'.the most puzzling thing is that when i use dbms_lob.FILEISOPEN to check whether i can access the file ,it returns 1 which means succeed . And dbms_lob.GETLENGTH() also returns the right value.
here is the testing code:
declare
     pFile bfile;
     sDir varchar2(255);
     sFileName varchar2(255);
     bExist integer := 0;
     Amount Integer := 4000;
begin
     sDir := 'SRC_PATH';
     sFileName := 'ele_onlinedoc.ico';
     pFile := bfilename(sDir, sFileName);
     --checking  file existence
     bExist := DBMS_LOB.FILEEXISTS(pFile);
     if bExist = 1 then
          dbms_output.put_line('File Exist');
     else
          dbms_output.put_line('File Not Exist');
     end if;
     --check file size
     Amount := dbms_lob.Getlength(pFile);
     dbms_output.put_line(TO_CHAR(Amount));
     if dbms_lob.FILEISOPEN(pFile) = 1 then
          dbms_output.put_line('File is already Opend');
     else
          dbms_output.put_line('File is closed');
     end if;
     dbms_lob.fileOpen(pFile,dbms_lob.file_readonly);
     dbms_lob.fileclose(pFile);
EXCEPTION
     When VALUE_ERROR then
          dbms_output.put_line('Exception Value_error');
     When OTHERS then
          dbms_output.put_line('Exception OTHERS');      
          dbms_output.put_line(to_char(SQLCODE));
          dbms_output.put_line(sQLERRM);
end;
OUTPUT:
File Exist
1078
File is closed
Exception OTHERS
-22288
ORA-22288: file or LOB operation FILEOPEN failed
we can see that file is detected and also we can get the right size(1078 byte) ,
but fail to open the file.
so what`s the problem .
thanks!

Answer 1

ORA-22288: file or LOB operation string failed string
Cause: The operation attempted on the file or LOB failed.
Action: See the next error message in the error stack for more detailed information. Also, verify that the file or LOB exists and that the necessary privileges are set for the specified operation. If the error still persists, report the error to the DBA.